Systemic mast cell disease (SMCD) and bone pain. A case treated with radiotherapy

Systemic mast cell disease (SMCD) is a rare disease characterized by a multitopic proliferation of cytologically and/or functionally abnormal tissue mast cells. SMCD preferentially involves the skin, spleen, liver, lymph nodes and the bone marrow. The cause of SMCD is unknown. Bony pain, caused by mast cell infiltration of the marrow cavity, is present in up to 28% of cases and is frequently chronic and difficult to palliate with medical therapy.

We report one case of refractory bone pain in a 54-year-old female Caucasian patient with advanced SMCD and associated bony involvement, which was treated with radiotherapy for pain palliation. Between 1995 and 1998, the patient was irradiated at four different locations: 1) right shoulder and proximal right humerus, 2) both hands, 3) both knees, 4) left humerus with a total dose of 40 Gy in 2.0 or 2.5 Gy daily fractions.

Different results of pain palliation were achieved. In one location the pain was reduced for 55 months until her death due to disease progression, whereas in two other locations a pain control was maintained for 3 and 6 months after radiotherapy. In one location, no pain reduction was achieved. Severe side effects were not observed.

Palliative radiotherapy has a role in the control of severe intractable bone pain in patients with advanced SMCD, though in some cases the effect may be short or incomplete. The observed palliation of pain can even differ in the same patient.